1. Field
This invention relates to medical devices, and, more particularly to internally deployed medical devices which can be used in naturally occurring or surgically created lumens, passageways, cavities, defects, holes, tissues, or other regions of the body. Such internally deployed devices include stents, embolic protection devices, guide wires, snares, catheters, neurovascular coils, septal defect closure devices, atrial appendage closure devices, staples, clips, etc. This invention also pertains to methods of manufacturing such medical devices and methods of using such medical devices.
2. Description of the Related Technology
The human body has many systems that include lumens in performing their function. The primary example is the vascular system, which transmits blood throughout the body through blood vessels having lumens. The body's breathing system, digestive system, reproductive system, nervous system and even skeletal system also have major or minor components comprised of lumens.
Almost since the beginning of surgery, surgeons have used the body's lumenal systems in medically treating the body. In some instances, the purpose of the surgery is to protect or repair the lumenal system itself. For instance, stents are commonly used to reinforce or hold open a blood vessel. In other instances, the surgical procedure uses the lumenal system to navigate through the body. In all instances in which surgical procedures are lumenally performed, the size of the lumen to some extent establishes the relative size of the medical devices being implanted or used during the surgery.
Internally deployed medical devices have been devised in a wide range of materials. Traditional metals such as stainless steel, originally used for a wide range of internally deployed medical devices, have been replaced in certain instances with other alloys, such as nitinol, ELGILOY, cobalt chrome alloys, tantalum, magnesium alloys, and other metals. In other instances, metal materials have been supplanted with polymeric, bio-polymeric, ceramic or bio-ceramic materials. These less traditional materials provide a variety of advantages. In some instances, materials such as nitinol are used due to their superelastic characteristics, and for their ability to be shape-set to a predetermined shape. Internally deployed implants can be bioabsorbable in whole or in part, or can release drugs or other active agents over time. Generally speaking, designers of internally deployed medical devices design new devices by considering materials which have already been used and approved in existing internally deployed devices. While internally deployed medical devices have greatly improved over the years, in part due to their improving designs and materials of construction, there is an ongoing opportunity for further improvement by using new materials and designs appropriate to the new materials.
Separate from the medical device field, many new materials are introduced to manufacturers. One type of such new material is amorphous metal or metal glasses. Amorphous metals are metals which have been transformed from an amorphous, molten state to a solid state at a speed or under conditions which prevent a crystalline atomic structure from evolving during the solidification process. Through work done at the California Institute of Technology (“Caltech”), the theoretical and actual physical existence of amorphous metals has been known since the 1960's. Still, actual implementation has been limited by the cooling speed necessary, which was only obtainable in samples having a thickness on the order of 100 microns or less. More recently, work done at Caltech and through companies such as Amorphous Technologies International (Laguna Niguel, Calif.) and Liquidmetal Technologies (Lake Forest, Calif.) has expanded the applicability of amorphous metals. For instance, U.S. Pat. Nos. 5,288,344 and 5,368,659, incorporated by reference, first disclose beryllium alloys which form metallic glass upon cooling below the glass transition temperature at a rate appreciably less than 1,000,000° C./sec. U.S. Pat. Nos. 5,618,359, 5,735,975 and 5,803,996, incorporated by reference, disclose alloys of titanium, zirconium and/or hafnium which form metallic glass upon cooling below the glass transition temperature at a rate appreciably less than 1,000° C./sec. U.S. Pat. Nos. 4,653,500, 5,976,274 and 6,325,868, incorporated by reference, disclose iron-based amorphous metal materials. U.S. Pat. No. 5,711,363, incorporated by reference, discloses alloys which form metallic glass upon cooling below the glass transition temperature at a rate appreciably less than 500° C./sec.
As there is currently a need to improve upon the medical devices formed from more traditional materials, it has been discovered that the physical properties of amorphous metal may be beneficial when used in internally deployed medical devices.